1. Field of the Invention
The subject invention relates generally to a gasket treated to reduce fuel permeation, and more specifically to a polymer gasket that is surface treated with a halogenated solution to substantially enhance the gasket's resistance to fuel permeability.
2. Related Art
In internal combustion engines, highly volatile fuel is used for the combustion process. Ever increasing emission regulations motivate engine and automobile manufacturers to minimize the escape of unburnt fuel to the environment. Typically, unburnt fuel escapes by permeating through static gaskets of the type used throughout an engine to seal various bolt-on components. Gaskets in the fuel delivery path are particularly vulnerable to fuel permissivity, but gaskets on the oil side of engines are also at risk. Because fuel mixes with engine oil up to 20% between oil changes, even an oil pan gasket is vulnerable to fuel permeation.
Gaskets made from plentiful, low-cost acrylic elastomers are typically used in non-fuel path applications. In order to reduce fuel vapor permeation through fuel path gaskets, the prior art has taught to manufacture those gaskets from fluorinated elastomers. Fluorinated elastomer materials, while effective as a fuel permeation barrier, are typically four times more expensive than the same gasket made from an acrylic elastomer. In other words, because of the high cost differential, gaskets made from a homogenous fluorinated elastomer material have been used mainly in intake manifolds and other fuel path applications. Whereas, the more cost effective acrylic, EPDM or HNBR elastomer gaskets tend to be used for valve covers, oil pan gaskets and the like where small amounts of fuel permeation have been considered tolerable.
Because of the heightened concern about the escape of fuel from engines for environmental reasons, there is a need to more completely outfit an internal combustion engine with gaskets resistive to fuel permeation. However, this desire must be offset by the high cost of prior art solutions which manufacture the entire gasket body from fluorinated elastomer.